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Is the unit a heatpump? amp draw max, current amp draw? Saying the units match up and proper 410a metering device installed. The compressor bypass valve can be open. TXV not properly working. If unit has a reversing valve.. I actually found a piece of solder stick inside the reversing valve of a brand new Trane.

The only way to get pressures like that is to have something bypassing... example of a TXV being wide open, or reversing valve stuck or if your compressor went out on high pressure I've seen the high pressure release valve that is internal to the compressor stay open. Most common of these problems would be the compressor bypass. Bypass might be stuck open or is coming open due to restriction of some kind.... If you're really unsure start grabbing pipes and activate/de-activate reversing valve. The compressor bypass even has a distinct sound to it. But about the amp draw if the RLA is say 28.8 and amp draw is only 6.0 then it's the bypass. Hopefully my blabbering is helping ...

Did you switch it over to heat??? That would help to eliminate a lot of possibilities.

175 and 300.....sounds like the reversing valve is stickin half way. Or jammed. Possibly low low voltage to coil. Or bad coil on valve. If it were me, I would eliminate the reversing valve as the culprit first. Sounds as if its stuck and leaking through.

Just my 2 cents. As far as heat pump, it no workie one way, first thing I do is switch it other way and do a quick check. It will save you buku time in the long run 9 times outta 10.

I fully support the military and the War on Terrorism.

If you don't know, then don't do. If you don't know and still do, then be prepared to pay someone else a lot to undo what you did and then do it right.

If you do know, then do. But do it right. Otherwise, you may not be doing it long.

The only way to get pressures like that is to have something bypassing... example of a TXV being wide open, or reversing valve stuck or if your compressor went out on high pressure I've seen the high pressure release valve that is internal to the compressor stay open. Most common of these problems would be the compressor bypass. Bypass might be stuck open or is coming open due to restriction of some kind.... If you're really unsure start grabbing pipes and activate/de-activate reversing valve. The compressor bypass even has a distinct sound to it. But about the amp draw if the RLA is say 28.8 and amp draw is only 6.0 then it's the bypass. Hopefully my blabbering is helping ...

I haven't personally seen too many resi TXV's stick wide open. Usually when they crap out, they close off and pull a vacuum.

Should check you superheat first. Make sure the valve is metering properly before you start tearin into that thing.

I fully support the military and the War on Terrorism.

If you don't know, then don't do. If you don't know and still do, then be prepared to pay someone else a lot to undo what you did and then do it right.

If you do know, then do. But do it right. Otherwise, you may not be doing it long.